Currently, it is known to use power adapters and chargers for charging or powering a variety of electronic devices having an on-board battery or power supply, and the chargers provide power to the battery. As used herein, the term “charger” refers to devices that provide a step in power (i.e., step power from an input voltage to an output voltage), convert power (i.e., convert input alternating current (AC) to output direct current (DC)) or both.
For an electrical device in the form of a laptop computer, for instance, the power cable assembly provided is essentially a charger, the cable assembly being detachable and including a “brick” with internal circuitry for converting power. The cable assembly generally has two connection points, a first one for receiving power such as from a power outlet and a second one for connecting with and conveying power to an input on the laptop computer itself. The first connection point is generally prongs or blades that are inserted into the power outlet for receiving power therefrom which, in the United States, is alternating current power. The second connection point is generally a connector plug removably received in a socket of the laptop. As examples, the input power may be alternating current of a first voltage (such as 110/120V), and the output power may be direct current of a second, generally lower, voltage such as 19.5V.
Because of their on-board power supply, many electrical devices are capable of providing an electrical signal corresponding to when the electrical device is turned on, though the devices are generally not equipped to specifically do so. For some electrical devices, such as laptop computers and at least some MP3 players, the electrical device itself is relied upon to power a separate device, such as a memory device commonly and variously referred to as a thumb drive or USB drive or USB plug that is connected (both physically and electrically for use as a memory device) via a USB connector on one end received in a USB port on the electrical device. When a laptop computer, for instance, is powered on, a USB plug connected with the laptop computer is automatically powered on by the laptop computer and typically includes an LED light that indicates such. When the laptop computer is turned off, it automatically turns off the USB plug, and the LED light turns off.
It is not uncommon for laptop computers to be disconnected from their power cable assemblies, as such are designed for portability, while the cable assembly itself remains connected with the power outlet. Accordingly, the cable assembly continues to draw power from the wall outlet. This power draw is one type of drain known as phantom load and is wasted energy. One of the reasons the cable assembly is left is because the intent for the use of the laptop is such that the on-board battery life (generally in the order of 2 to 4 hours) is sufficiently long for the user to return the laptop to the cable assembly before the life is reached. Other reasons may be that the user transports the laptop computer between two different sites at which separate cable assemblies are maintained, such as an office and a home. In any event, it is not uncommon for the cable assembly to be secured with the power outlet, with the remote first connection plug or prongs, in a manner that makes it tedious or difficult to unplug the cable assembly from the outlet when the laptop is disconnected, such as when the outlet is behind furniture or the cable assembly is routed through office furniture.
Accordingly, a user may plug the cable assembly prong into the power outlet of their choice (whether it is behind furniture or some other obstruction), and may leave the connector end for the electrical device in a place that is convenient for connecting and disconnecting the electrical device. However, by leaving the cable assembly connected with the outlet, power draw continues. To be more precise, this draw is phantom load, that is, residual power consumption by power cable assemblies or other devices when not connected to their host electronic device (i.e., a laptop computer), or when the electronic device is shut off.
Phantom load is becoming a greater issue for the public. Electrical devices that result in the described phantom load are continually increasing in per capita usage, populations increase exponentially, and great portions of the world's population are gaining the discretionary capital that enables the purchase of such devices. Energy is becoming more expensive on a monetary basis, and energy production overwhelmingly has an environmental impact, such as fossil fuel or nuclear energy.
Extensive effort has been and continues to be put into development of energy-efficient devices of all sorts. The “Energy Star” program sponsored by the United States Environmental Protection Agency and the United States Department of Energy is well known, though principally for energy efficiency appliances and building products such as glass doors and windows. In parallel with Energy Star standards efforts, a variety of state and federal laws have been enacted that are directed toward external power-supply products, which includes power devices or chargers for portable electronic devices.
Nokia has announced a prototype device from Nokia that operates with a mechanical switch. Specifically, the Nokia device has a housing end receivable in a power receptacle and including internal circuitry for the charger/adapter functions. A button is located on the housing for turning the Nokia device on, and the circuitry automatically turns off by releasing the button.
In order to be a true “zero-waste” device, the power input (i.e., AC input) to the power device itself must be cut. Therefore, the location within the circuit at which the power is cut is central. In other words, a switch that merely cuts the output power from the connector (such as might be used to prevent overcharging of a battery) while the converter/adapter circuitry remains under power is not a “zero-waste” device because the internal circuitry is allowed to draw power, the effect being no different than simply removing the electronic device itself.
The paradigm for Nokia, then, appears to be to provide a “zero-waste” device by having the switch co-located with the input to the charger. However, as the use of many detachable power chargers is described above, the charger input is often in a difficult-to-reach position, resulting in people not bothering to unplug the device. The Nokia device still requires access before and after use to turn the device on and off.
Accordingly, it is desirable and there is a need for an improved power device, charger or otherwise, for reducing phantom load when a portable electrical device is turned off or disconnected from the power cable assembly or power device or otherwise not intended to be drawing power from the power device. It is also desirable to provide a device that allows disconnection of power to an electrical device, the electrical device continuing to utilize its manufacturer-supplied power cord.